Weightlifting Barbell

ABSTRACT

A weightlifting barbell includes a steel shaft and sleeves constructed of engineered plastic (e.g., POM, Teflon®, Nylon, UHMW, and the like). The engineered-plastic sleeve is relatively light weight and provides impact strength suitable for executing weightlifting exercises.

BACKGROUND

Various types of weightlifting barbells are known. Typically, a barbell includes a main shaft that is configured to support weights (e.g., weightlifting plates) on each side. One particular style of weightlifting barbell includes sleeves on each end of the main shaft that support the weightlifting plates.

Various styles of barbells exist, and some styles are designed to be used to perform certain weightlifting exercises. For example, one style of barbell is designed to be used to perform the Olympic lifts, known as the clean-and-jerk and the snatch. Barbells that are used to perform the Olympic lifts often include dimension that fall within a common range of dimensions. For example, it is common that the barbell includes a shaft having a diameter that is between about 25 mm and about 29 mm (about 1 inch to about 1.14 inches). In addition, it is common for the sleeves of the barbell to have a diameter of about 50 mm (about 1.97 inches). Further, it is common that the sleeves be spaced apart by a distance of about 131 cm (about 51.5 inches).

Barbells are usually constructed of some type of metal, such as steel (e.g., steel alloy) or aluminum. In some barbells, both the shaft and the sleeves are made from the same or similar metal. That is, both the shaft and the sleeves are made from a type of steel or are made from a type aluminum.

Barbells including steel shafts and steel sleeves can vary in weight depending on various factors, such as the length of the shaft and the sleeves and diameter of the shaft. These types of barbells typically include a weight amount that is between about 15 kg and about 20 kg (about 30 pounds to about 45 pounds). Barbells including aluminum components are often lighter than steel barbells; however, barbells having aluminum components sometimes have a limited capacity for supporting weight plates and are sometimes not as tough or rugged, based in part on a length to diameter ratio. In addition, an aluminum shaft does not necessarily mirror the feel and performance of a steel shaft in various respects.

SUMMARY

At a high level, this invention is directed to a barbell that includes a metal shaft and engineered-plastic sleeves. In another embodiment, the present invention is directed to an engineered-plastic sleeve having features allowing it to be coupled to a shaft to support weight plates. Embodiments of the invention are defined by the claims below, not this summary. A high-level overview of various aspects of the invention are provided here to provide an overview of the disclosure and to introduce a selection of concepts that are further described below in the detailed-description section below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in isolation to determine the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings form a part of the specification, are to be read in conjunction therewith, and are incorporate by reference in their entirety. In the drawings:

FIG. 1 depicts a barbell in accordance with an embodiment of the present invention;

FIG. 2 depicts a cross section of a barbell in accordance with an embodiment of the present invention;

FIG. 3 depicts a cross section of a sleeve and a portion of a shaft in accordance with an embodiment of the present invention; and

FIG. 4 depicts a cross section of a sleeve and a portion of a shaft in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION

The subject matter of embodiments of the present invention is described with specificity herein to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent. Rather, it is contemplated that the claimed subject matter might also be embodied in other ways, to include different elements or combinations of elements similar to the ones described in this document, in conjunction with other present or future technologies.

Referring now to FIGS. 1 and 2, an embodiment of the present invention is depicted. FIGS. 1 and 2 depict a barbell 10, which includes a shaft 12, a first sleeve 14, and a second sleeve 16. The barbell 10 of the present invention might be used to perform various weightlifting exercises, either with or without weight plates loaded on the sleeves. For example, the barbell 10 might be used to perform the Olympic lifts, known as the clean-and-jerk and the snatch. In the clean-and-jerk, the barbell is lifted (i.e., cleaned) from the ground (or from a position about 22 cm off the ground when the barbell is loaded with about 45 cm diameter weight plates) to about shoulder height. From the shoulder height, the barbell is “jerked” overhead. When performing the snatch, the barbell is lifted from the ground to an overhead position in one motion.

Other types of exercises might also be performed with the barbell 10. For example, the barbell 10 might be used to perform various training exercises that are directed to improving or practicing technique in the Olympic lifts, improving body mobility, and improving the strength of the lifter. Examples of technique drills include the Burgener warm-up and snatch skills transfer exercises, such as the snatch press, overhead squat, snatch push press, pressing snatch balance, snatch balance, heaving snatch balance, SOTS press, and the like. When performing these types of exercise, it is common for the lifter to lift the barbell directly over his or her head. From the overhead position, the barbell is either lowered to the ground, or is often times dropped to the ground from the overhead position. Other weightlifting exercises might also be performed using the barbell 10, such as back squat, front squat, deadlift, bench press, shoulder press, and the like.

As depicted in FIG. 2, the shaft includes a first end portion 18, which is received within a bore 20 of the first sleeve 14, and a second end portion 22, which is received within a bore 24 of the second sleeve 16. The shaft 12 also includes a central region 28, which is positioned between the first sleeve 14 and the second sleeve 16.

In a further aspect, the first sleeve 14 includes a weight-receiving portion 30 and a flange portion 32, both of which are generally cylindrical in shape. The weight-receiving portion 30 is sized to slide through a center hole of a weightlifting plate, and the flange 32 impedes the weightlifting plate from sliding axially inward past the first sleeve 14. Similar to the first sleeve, the second sleeve 16 includes a weight-receiving portion 34 and a flange portion 36.

The barbell 10 might include various dimensions, depending on an intended use and desired overall barbell weight amount. For example, in one embodiment, the shaft 12 includes a diameter in a range of about 25 mm to about 29 mm, and the first sleeve 14 and the second sleeve 16 are spaced apart by a distance 26 of about 131 cm. Moreover, the overall length of the shaft might be in a range between about 131 cm and about 214 cm. In other embodiments, the overall length of the shaft might be shorter or longer than this range.

In addition, the dimension of the first sleeve 14 and the second sleeve 16 might also vary depending on the intended use and desired overall barbell weight amount. For example, in one embodiment, the weight-receiving portions 30 and 34 include an outer diameter in a range of about 49 mm to about 51 mm. This is one exemplary range, and in other embodiments, the diameter of the weight-receiving portions 30 and 34 is sized to fit through the center hole of a weight plate. The outer diameter of the flanges 32 and 36 might vary, so long as the diameter is larger than the diameter of the weight-receiving portions 30 and 34, thereby creating a shoulder at the interface between each weight-receiving portion 30, 34 and respective flange portion 32, 36.

In a further embodiment, the length of the sleeves 14 and 16 might vary. For instance, FIG. 2 depicts an embodiment in which each sleeve extends beyond a respective end of the shaft 12 (see also FIG. 4 for an exemplary illustration). However, in an alternative embodiment, the sleeves might have a length which results in an end of the sleeve being substantially even with the end of the shaft (see also FIG. 3 for an exemplary illustration).

In another embodiment, a configuration of the sleeves 14 and 16, as well as the system by which the sleeves 14 and 16 attach to the shaft 12, enables a weight plate to axially rotate. That is, when a weight plate is loaded on one of the weight-receiving portions 30 or 34, the weight plate is permitted to rotate around an axis of the weight plate. For example, the weight plate might rotate respective to the sleeve on which the weight plate is loaded. In another embodiment, the sleeve on which the weight plate is loaded rotates respective to the shaft 12. The extent to which the weight plate rotates respective to the sleeve and/or the sleeve rotates respective to the shaft 12 depends, at least in part, on the material(s) from which the sleeve and shaft are constructed and the system with which the sleeve is attached to the shaft 12. Axial rotation of a weight plate when loaded on the barbell is useful to reduce torque and stress on a lifter (e.g., lifter wrists) when the lifter performs certain exercises (e.g., snatch, clean-and-jerk, and other exercises described herein) with the barbell.

In a further embodiment, the barbell 10 is constructed of certain materials. For example, in one embodiment, the shaft 12 is constructed of steel or an alloy steel and includes a solid round bar. A wide variety of steels exist that might be selected based on physical properties, such as tensile strength. For example, in one embodiment, an alloy steel might be selected that has a tensile strength above 50,000 psi. This is merely an example, and some alloy steels that might selected have a higher tensile strength (e.g., above 200,000 psi).

Steel is sometimes desirable instead of other metals based on a combination of properties, such as density and tensile strength, which allow steel shafts to exhibit certain characteristics (e.g., strength and/or weight bearing) at a certain length, diameter, and/or total barbell weight amount. For instance, steel often provides amount of strength that is suitable for weightlifting exercises, as well as a suitable total barbell weight, if it is desirable to have a barbell with approximately 131 cm between sleeves. In addition, the properties of steel can provide an amount of flex or spring in the shaft when the barbell is being used to execute certain lifts.

When the shaft 12 is constructed of alloy steel, a shaft length might be selected based on a targeted overall barbell weight, taking into consideration the weight amount of the sleeves and the diameter of the shaft 12. For example, in one embodiment, if an overall barbell weight amount of 7.5 kg (about 16.53 lbs.) is desired, then the shaft having a diameter of 25 mm might include a length of about 170 cm, such that the shaft weighs about 6.75 kg. These dimensions will ultimately depend on the type of alloy steel selected, as each alloy steel might include a different respective density. In another embodiment, one or more of the shaft dimensions (e.g., diameter and/or length) might be modified to achieve other desired weight amounts, such as 15 lbs. (about 6.8 kg), 20 lbs. (about 9.07 kg), or 10 kg (about 22.04 lbs.). As described in other parts of this description, the shaft might include a length in a range of about 131 cm to about 214 cm, the length being selected to achieve a desired weight amount.

The shaft 12 might be constructed of alloy steel to obtain the various benefits of steel. As described above, some of these benefits include the ability of the barbell to support weight plates without breaking when the barbell is lifted and dropped. Steel is heavier than other types of shaft materials (i.e., has a higher density). Thus, absent the present invention, it can be challenging to construct a barbell with a steel (or alloy steel) shaft that also includes a relatively low overall barbell weight amount. For example, an about 25 mm steel shaft that is about 170 cm long includes a weight amount of about 6.547 kg. Absent the present invention, it can be challenging to construct a barbell that includes a steel shaft having these exemplary dimensions and that includes an overall weight amount of about 7.5 kg. These dimensions are exemplary of an embodiment of the present invention, and it is to be understood that the present invention includes barbells having steel shafts of various diameters and lengths.

In an embodiment of the present invention, the sleeves 14, 16 are constructed of an engineered plastic. Examples of engineered plastics include polyoxymethylene (POM or acetal), variations of nylon, Teflon, and various types of polyethylene. For example, one possible type of polyethylene includes ultra-high-molecular-weight polyethylene (UHMW). These are merely examples of engineered plastics, and various other engineered plastics might also be used based on desired characteristics, such as impact strength, coefficient of friction, compressive strength, thermal expansion properties, wear-resistance properties, and the like. Because many engineered plastics typically have a lower density than other materials used to construct barbell sleeves (e.g., steel or aluminum), sleeves 14, 16 constructed of engineered plastics include a lower weight amount, which helps to lower the overall weight amount of the barbell 10. For instance, polyethylenes typically have a density that is about 0.88 g/cm³ to about 0.95 g/cm³, and here are approximate densities of various engineered plastics: UHMW—about 0.93 g/cm³; HDPE—about 0.94 g/cm³; polyoxymethylene—about 1.4 g/cm³; Nylon—about 1.15 g/cm³; Teflon—about 2.2 g/cm³. The densities of these engineered plastics are less than aluminum, which is typically about 2.7 g/cm³, and less than carbon steel, which is typically about 7.85 g/cm³, such that a sleeve of the same size weighs less when made from an engineered plastic, as compared with these metal alternatives.

In one embodiment of the present invention, the sleeves 14, 16 are constructed of UHMW including desired properties. For example, in one embodiment, the UHMW provides a coefficient of friction (Dry vs. Steel) of about 0.12. The coefficient of friction properties of UHMW provides various benefits when the UHMW is used to construct a barbell sleeve. For example, relatively low friction of UHMW (as compared with other materials such as various metals) allows UHMW sleeves to slide when the UHMW sleeves rotate around the barbell shaft (as described above). As such, in one embodiment, bearings (e.g., needle roller bearings, ball bearings, and the like) are not positioned between the sleeve and the shaft 12 to facilitate sleeve rotation. Other engineered plastics include desirable coefficients of friction and thus might likewise be selected to construct the sleeves.

In a further embodiment, the sleeves 14, 16 are constructed of an engineered plastic that provides a desired amount of impact strength. For example, one measure of impact strength includes the Izod Impact Test. As such, the sleeves 14, 16 might be constructed of UHMW that includes a “no break” rating when subjected to a single notch Izod Impact Test. Other engineered plastics include desirable impact strengths and thus might likewise be selected to construct the sleeves. In an embodiment of the present invention, the impact strength of selected engineered plastics (such as UHMW among others) is sufficient enough that a sleeve constructed of the engineered plastic will not break due to the impact of the barbell hitting the ground when loaded with weight plates and dropped from an overhead position (e.g., about 200 cm or 78 inches above the ground).

In a further embodiment, the sleeves are constructed of an engineered plastic that provides a desired amount of wear resistance (i.e., abrasion resistance). That is, because a sleeve constructed of engineered plastic might be axially rotating on the shaft, or a weight plate might be axially rotating on the sleeve, an amount of wear resistance slows the erosion (if any) of the sleeve. In one embodiment, the sleeves are constructed of an engineered plastic that has better wear-resistance properties than steel. In another embodiment, the sleeves are constructed of an engineered plastic that has better wear-resistance properties than aluminum. One possible measure of wear resistance includes a sand-slurry rating. Thus, in an embodiment of the present invention, the sleeve is constructed of an engineered plastic that has a better sand-slurry rating than steel, than aluminum, or than both steel and aluminum. In a further embodiment, the sleeve is constructed of UHMW having a better sand-slurry rating than steel (e.g., carbon steel and/or alloy steel).

In an embodiment of the present invention, the engineered plastic that is used to construct the sleeves is selected to optimize one or more of the coefficient of friction properties, the impact strength properties, and the abrasion-resistance properties. In addition, the design of the sleeve minimizes thermal-expansion properties. For example, certain clearances might be provided between the sleeve and other barbell components, such as the shaft and retaining rings, to allow for expansion of the sleeve under higher temperatures. Further, on account of the relatively low density of engineered plastics (relative to metals), constructing sleeves of engineered plastic results in a lower overall barbell weight.

Referring now to FIG. 3, exemplary barbell elements are depicted in accordance with an embodiment of the present invention. For example, in FIG. 3, the sleeve 14 is coupled to an end portion 18 of a shaft. In addition, the sleeve 14 includes a weight-receiving portion 30, which includes a diameter in the range of about 49 mm to about 51 mm, and a flange 32. A shoulder 40 between the weight-receiving portion 30 and the flange 32 helps to impede a loaded weight from sliding inwardly. As such, the sleeve 14 includes a proximal end (e.g., end of flange 32) oriented towards a central portion of the shaft 12 and a distal end (opposing end of weigh-receiving portion 30) that is opposite the proximal end.

The bore that extends from one end (e.g., proximate end) of the sleeve 14 to the other end (e.g., distal end) of the sleeve 14 includes a first region 44 (e.g., central region), which includes a first diameter. The first diameter provides a sufficient clearance to allow the interior bore surface of the first region 44 rotate about the shaft. That is, in FIG. 3, the interior bore surface of the first region 44 slides directly on the shaft when the sleeve rotates on the shaft, such that the sleeve 14 does not require rotation on a bearing. In addition, the first diameter is sufficient, such that when the sleeve expands in higher temperatures, the sleeve does not bind on the shaft. In one embodiment, the clearance between the first region and the shaft is in a range of about 0.1 mm and 0.4 mm (on either side). As such, first diameter is about 0.2 mm to 1.0 mm larger than the diameter of the shaft.

Various structures are positioned to retain the sleeve 14 on the shaft. For example, FIG. 3 depicts an external retaining ring 42 coupled in a groove cut into the shaft. As such, the sleeve 14 includes a second region 46 (e.g., proximal-end region) that is axially adjacent to the first region 44 and that includes a second diameter, which is larger than the first diameter. The second diameter is larger in-part to provide sufficient clearance for the retaining ring 42. Thus, a shoulder 48 is positioned at an interface between the first region 44 and the second region 46. The retaining ring 42 engages the shoulder 48 to impede the sleeve 14 from sliding axially inward toward a center of the shaft. In addition, the sleeve 14 includes a disc 50, which is pinned to the end portion of the shaft. Because the disc 50 is pinned, the disc is fixedly secured to the shaft, such that the disc impedes the sleeve 14 from sliding outwardly and off of the end of the shaft and does not axially rotate about the shaft. The disc 50 might be made of the same engineered plastic as the sleeve 14 or some other material, such as steel or aluminum.

The overall length of the sleeve 14 varies depending on various factors, such as the overall length of the shaft and the width of the disc 50. For example, in one embodiment in which the shaft includes as overall length of about 170 cm, the combined overall length of the sleeve 14 and the disc is between about 19 cm and about 19.635 cm. In a further embodiment, bore of the second region 46 is deep enough to protect the retaining ring 42. For example, the second region 46 might include a depth of about 0.125 inches to about 0.25 inches.

Referring now to FIG. 4, another embodiment of the present invention is depicted. In FIG. 4, the embodiment depicted includes some elements that are similar to the embodiment depicted in FIG. 3, such as the first bore portion 44 having the first diameter and the second bore portion 46 having the second diameter, which is larger than the first diameter to create the shoulder 48 and to house the retaining ring 42. However, FIG. 4 depicts an alternative retention system used to prevent the sleeve 14 from sliding off of the end of the shaft 12.

In FIG. 4, the sleeve 14 includes a third bore region 52 including a third diameter that is larger than the first diameter of the first bore region 44. As such, a shoulder 54 is positioned at an interface between the first bore region 44 and the third bore region 52. Another retaining ring 56 is coupled to a groove in the shaft 12, and the retaining ring 56 engages the shoulder 54 to impede the sleeve 14 from sliding off of the end portion 18 of the shaft 12.

In an embodiment of the present invention depicted in FIG. 4, the sleeve 14 includes a length that causes the sleeve 14 to extend beyond the end portion 18 of the shaft 12. For example, the sleeve 14 might extend beyond the shaft by at least about 2 cm. In one embodiment, the sleeve 14 includes a total overall length of about 21 cm. As such a hollow portion 58 is exists in the third bore region 52. In one embodiment, the end 18 of the shaft 12 is covered by positioning a cap or plug in the hollow portion 58. For example, the cap or plug might include a friction fit or might be screwed into position. In addition, a disc-like cover (not shown) might be held in place in the hollow portion 58 using an internal retaining ring (not shown) that snaps into a groove cut in the internal surface of the third bore portion 52.

The first bore 44 of the sleeve includes a bore length extending from the proximal shoulder 48 to the distal shoulder 54. In an embodiment of the present invention, the first bore 44 includes a substantially constant diameter extending from the proximal shoulder 48 to the distal shoulder 54. In a further embodiment, the first bore 44 having a substantially constant diameter is longer than the other bores (e.g., 52 or 46). In another embodiment, the bore length of the first bore 44 is in a range of about 5 inches to about 7.5 inches. In a further embodiment, the bore length of the first bore 44 is in a range of about 7 inches to about 7.25 inches. In another embodiment, the first bore 44 includes a length of about 7.1875 inches, the second bore includes a length of about 0.25 inches. The third bore includes a length that extends beyond the end of the shaft, and in one embodiment the third bore includes a length that is determined based on a desired overall barbell length and/or a desired overall sleeve length. For instance, if the first bore is about 7.1875 inches and the second bore is about 0.25 inches, then a third bore might have a length of about 0.8125 in order to create a sleeve that is about 8.25 inches long or 0.6875 inches in order to create a sleeve that is about 8.125 inches long. But the loadable length of the sleeve (i.e., length able to load weight plates) will also depend on the width of the flange.

In an alternative embodiment of the present invention, a barbell includes an aluminum shaft and engineered-plastic sleeves. While an aluminum shaft might not mirror steel in some respects, it does offer various characteristics that make it suitable for use in constructing a barbell for various uses. In one embodiment, the barbell includes an aluminum shaft (e.g., 6061 alloy) that has a diameter of about 25.4 mm (1 inch) and a length of about 121.9 cm (48 inches). As such, the shaft of the barbell includes a shaft weight of about 1.67 kg (3.69 pounds).

In a further embodiment, a shaft having these exemplary dimensions is combined with an engineered-plastic sleeve (e.g., as described herein in FIG. 4), to construct a barbell having a total barbell weight of about 2.268 kg (5 pounds). That is, an aluminum shaft might be fabricated to include the retention system described with respect to FIG. 3 or 4 in order to be assembled together with the sleeves described in those figures. In one embodiment, proximal retaining grooves are positioned in a range of about 7.5 inches to about 7.75 inches from a respective end of the aluminum shaft to retain a ring 42, which engages the proximal shoulder 48 of the sleeve. Accordingly, the aluminum barbell might have a distance between sleeves of about 32 inches to about 33 inches (about 81 cm to about 83.5 cm). In a further embodiment, a barbell having these features (e.g., distance between collars of about 32 inches, total barbell weight of about 5 pounds, and total overall length of about 48 to about 50 inches) is useful for users that might not be as strong and/or have shorter arms and wingspans (e.g., younger lifters). The combination of aluminum shaft and engineered-plastic sleeve contributes to some of the features of the barbell, including a desirable overall weight and a desirable length between sleeves. In contrast to an embodiment of the present invention, in order to construct a barbell made entirely of aluminum that only weighs about 5 pounds, the barbell might have a length that is shorter than 32 inches.

In both FIG. 3 and FIG. 4, an internal bore surface of the first bore potion 44 (e.g., central region) functions as a bearing surface, which slides directly against the shaft 12 when the sleeve 14 axially rotates. As indicated in other portions of this description, a coefficient of friction of engineered plastics enables the sleeve 14 to rotate directly against the shaft. In other embodiments, a needle roller bearing or other type of bearing might be used in lieu of, or in combination with, the bearing surface provided by the first bore portion 44. That is, a bearing might be positioned inside the bore of the sleeve, such that the bearing at least partially circumscribes the shaft and reduces friction between the sleeve and the shaft. It is to be understood that while only a single sleeve 14 is depicted in FIGS. 3 and 4, the other sleeve 16 would include a substantially similar construction.

In a further embodiment, a diameter of the end portion of the shaft, which is received inside the sleeve, is substantially similar to the diameter of the portion of the shaft that is not received in the sleeve. That is, the portion of the shaft received inside the sleeve is not turned down to a diameter less than the portion of the shaft not received in the sleeve. Constructing the shaft to include a diameter that is substantially consistent from one end to the other reduces manufacturing costs associated with turning down the shaft. In addition, a consistent-diameter shaft avoids possible shaft weakness that might be created at the juncture at which the shaft is turned down (shoulder).

In other embodiments, it might be preferable to turn down the shaft to create room for a bearing to be inserted between the sleeve and the shaft or to create a shoulder on the shaft that helps to impede the sleeve from sliding axially inward toward a central portion o the shaft. In such an embodiment, a sleeve constructed of an engineered plastic is still utilized to take advantages of a low-weight sleeve that has sufficient impact strength to support weight plates and that includes high abrasion resistance.

The sleeve can be constructed using various manufacturing techniques. For example, in one embodiment the sleeve is turned from a piece of stock. In another embodiment, the sleeve is injection molded or compression molded.

Described above is a barbell that provides various advantages based on the combination of a steel shaft with sleeves constructed of an engineered plastic. For example, the combination of the steel shaft and impact strength of the sleeve enable the barbell to support weightlifting plates (e.g., bumper plates) when the barbell is lifted and dropped from an overhead position or is used to perform other traditional weightlifting exercises (e.g., squat, press, deadline, and the like). In addition, the density of the engineered plastic creates a lighter weight sleeve and lighter weight barbell, which is usable in various contexts (e.g., youth lifter, novice lifter, technique practice, mobility training, and the like). Because the barbell includes an overall weight that is manageable for many users, it can be used in various contexts (e.g., warm-up movements, technique training, youth training, new lifter training, physical rehabilitation, and the like). However, because the combination of the steel shaft and engineered-plastic sleeves possess certain strength attributes, the barbell can be loaded with weight plates and used to perform exercises without damage.

Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the scope of the claims below. Embodiments of our technology have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to readers of this disclosure after and because of reading it. Alternative means of implementing the aforementioned can be completed without departing from the scope of the claims below. Certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations and are contemplated within the scope of the claims. It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not limiting. 

Claimed is:
 1. A barbell comprising: a shaft including a first end portion and a second end portion, the shaft constructed of alloy steel and including a length of at least about 132 cm and a shaft diameter in a range of about 25 mm to about 29 mm; and a first sleeve attached to the first end portion and a second sleeve attached to the second end portion, wherein the first sleeve and the second sleeve each comprises: a proximal end oriented toward a central portion of the shaft and a distal end that is opposite the proximal end, and a bore extending from the proximal end to the distal end, the bore receiving a respective end portion of the shaft, and wherein the first sleeve and the second sleeve are constructed of ultra-high-molecular-weight polyethylene (UHMWPE).
 2. The barbell of claim 1, wherein the bore of each sleeve includes one or more bore diameters between the proximal end and the distal end and wherein no diameter of the one or more bore diameters is less than any diameter of the shaft.
 3. The barbell of claim 1 further comprising, a first retaining ring and a second retaining ring coupled to the shaft, wherein the first retaining ring impedes the first sleeve from moving axially inward toward a center-region of the shaft, and wherein the second retaining ring impedes the second sleeve from moving axially inward toward the center-region of the shaft.
 4. The barbell of claim 3, wherein the bore of each sleeve comprises a proximal-end region having a first diameter and a central region, which is axially adjacent to the proximal-end region and includes a second diameter, wherein the first diameter is larger than the second diameter, such that a first shoulder is positioned at an interface between the proximal-end region and the central region of the first sleeve and a second shoulder is positioned at an interface between the proximal-end region and the central region of the second sleeve, and wherein the first retaining ring impedes the first sleeve by engaging the first shoulder and the second retaining ring impedes the second sleeve by engaging the second shoulder.
 5. The barbell of claim 1, wherein the respective bore of the first sleeve and the second sleeve includes a bore diameter that is in a range of about 0.2 mm-1.0 mm greater than the shaft diameter.
 6. The barbell of claim 5, wherein a portion of the bore that includes the bore diameter includes a length that is equal to or greater than about 17 cm.
 7. The barbell of claim 1, wherein the barbell is bearingless.
 8. The barbell of claim 1, wherein each of the first sleeve and the second sleeve includes a respective interior-wall surface, which circumscribes the bore, and wherein the respective interior-wall surface slides directly against the respective end portion of the shaft when the first sleeve and the second sleeve rotate about the shaft.
 9. The barbell of claim 1 further comprising, a bearing positioned inside the bore, wherein the bearing at least partially circumscribes the respective end portion of the shaft.
 10. A barbell sleeve comprising: a sleeve body including a cylindrical weight-receiving portion having a first outer diameter between about 49 mm and about 51 mm and a cylindrical flange having a second outer diameter, which is larger than the first outer diameter, wherein the body is constructed of ultra-high-molecular-weight polyethylene (UHMWPE); and a bore extending from a first end of the body to a second end of the body that generally opposes the first end.
 11. The barbell sleeve of claim 10, wherein the bore includes a first bore section having a first bore diameter and a second bore section that is axially adjacent to the first bore section and that includes one or more second bore diameters, and wherein the one or more second bore diameters are greater than the first bore diameter and the second bore section extends from the first bore section to one of the first end or the second end of the body.
 12. The barbell sleeve of claim 11, wherein the second bore extends from the first bore section to the first end of the sleeve body, and wherein the cylindrical flange is positioned at the first end, such that the cylindrical flange circumscribes at least part of the second bore section.
 13. The barbell sleeve of claim 11, wherein the first bore section includes a length that is at least half of a length of the cylindrical weight-receiving portion.
 14. A barbell comprising: a shaft including a first end portion and a second end portion, the shaft constructed of alloy steel and including a length of at least about 132 cm and a shaft diameter in a range of about 25 mm to about 29 mm; and a first sleeve attached to the first end portion and a second sleeve attached to the second end portion, wherein the first sleeve and the second sleeve are each constructed of an engineered plastic and each comprises: a proximal end oriented toward a central portion of the shaft and a distal end that is opposite the proximal end, a bore extending from the proximal end to the distal end, the bore receiving a respective end portion of the shaft, and an internal bore surface that at least partially extends the length of the bore and that provides a bearing surface, which slides directly on the shaft when the sleeve axially rotates on the shaft.
 15. The barbell of claim 14, wherein the engineered plastic includes polyoxymethylene (POM), nylon, Teflon, or ultra-high-molecular-weight polyethylene (UHMW).
 16. The barbell of claim 15, wherein the engineered plastic is UHMW.
 17. The barbell of claim 14, wherein the bore of each sleeve includes one or more bore diameters between the proximal end and the distal end and wherein no diameter of the one or more bore diameters is less than any diameter of the shaft.
 18. The barbell of claim 14 further comprising, a first retaining ring and a second retaining ring coupled to the shaft, wherein the first retaining ring impedes the first sleeve from moving axially inward toward a center-region of the shaft, and wherein the second retaining ring impedes the second sleeve from moving axially inward toward the center-region of the shaft.
 19. The barbell of claim 18, wherein the bore of each sleeve comprises a proximal-end region having a first diameter and a central region, which is axially adjacent to the proximal-end region and includes a second diameter, wherein the first diameter is larger than the second diameter, such that a first shoulder is positioned at an interface between the proximal-end region and the central region of the first sleeve and a second shoulder is positioned at an interface between the proximal-end region and the central region of the second sleeve, and wherein the first retaining ring impedes the first sleeve by engaging the first shoulder and the second retaining ring impedes the second sleeve by engaging the second shoulder.
 20. The barbell of claim 1, wherein the barbell is bearingless. 